This invention relates to a bottomhole assembly (BHA) for use in well operations, with particular application to use in drilling with a downhole drilling motor and coiled tubing, and the invention relates to related methods of use of a BHA
The B J Nowsco directional drilling-using-coiled-tubing (D U C T) is an on-bottom orientation and steering system for the tool string. The orient-while-drilling system provides joystick drilling. The heart of the system, that which enables orient-while-drilling, or on-bottom orientation/steering, or joystick drilling, is a downhole electric-over-hydraulic power pack. This B J Nowsco power pack when combined with a rotating tool can generate torque greater than the reactive torque of the drilling motor. This torque should be greater than at least 700 foot pounds and preferably greater than 1,000 foot pounds. The downhole electric-over-hydraulic power pack can also be advantageously used to power other downhole tools, other than a rotating tool or an orienting tool, such as a circulating valve, or other valves. Also for example, the power pack could power an emergency release tool. The power pack could power a form of orienting tool that varied the offset of an offset joint, such as bent sub angle. (Rams or cams, as well as bents subs, can form species of offset joints, as that term is used herein.)
The power pack is preferably powered by an electric line that runs through coiled tubing. Running an electric line through coil instead of hydraulic lines has several advantages, one being space. Reversible DC motors are preferably selected for the electric motors. Given space constraints, preferably three DC motors would be run in sequence. In a preferred embodiment a hydraulic pump is placed both above and below three DC motors. A clutch is provided for each pump, so that when the motors are run in one direction one of the two hydraulic pumps generates hydraulic pressure in its line while the clutch slips the other pump. When the electric motors are run in the opposite direction, the other clutch slips and the first clutch engages so that the other hydraulic motor generates pressure in its line. The availability of two hydraulic lines facilitates powering double acting pistons. Check valves can be used to lock double acting pistons in place. High pressure relief valves can be used to differentially run second and third systems off the same hydraulic line as the first system. For instance, a first level of pressure could be used to move a piston relating to a rotating orienting member. If the piston were moved to one of its end positions and pressure subsequently built up, a relief valve could open that would allow the hydraulic fluid to then operate a circulation valve, for instance, or a second double acting piston system. A third relief valve could be placed on the same hydraulic line such that after the second piston had been moved to its stop position, pressure further builds up to open a third valve and to permit the hydraulic line to adjust the degree offset of an offset tool, for example, by running a third piston system.
A further aspect of the invention derives from the high level of torque generated by the downhole electric-over-hydraulic power pack when combined with a rotary orienting tool. An orienting tool including a rotating member may preferably be utilized to rotate a bent sub or any other species of offset sub. The high pressure utilized to generate a sufficiently high torque on the rotating member to rotate while drilling has led to the development of a xe2x80x9cbalanced pressurexe2x80x9d rotating member. Balancing the pressure on the rotating member avoids placing excessive force on thrust bearings supporting the rotating member. xe2x80x9cBalanced pressurexe2x80x9d is used to refer to a design wherein a helical surface receiving the pressure or force from the piston in one longitudinal direction is part of the member that also experiences a counter balancing force in the longitudinal direction due to the hydraulic fluid in the piston chamber. One way to attempt to express this xe2x80x9cbalanced pressurexe2x80x9d design is to state that the piston chamber is located in the unit that contains the helical gears that mate with the helical gears on the piston.
A further feature of the high powered orient-while-drilling system comprises the use of helical gears. The piston imparting rotational movement to a rotating member to orient an offset joint (such as a bent sub) preferably uses helical gears mating with similar gears on the rotating member, in lieu of a lug or key in helical slot system. Helical gears transmit rotational movement to the rotating member. Helical gears can be viewed as a key in helical slot system, and vice versa, wherein the contact surface area between the key and slot has been substantially extended.
A further inventive aspect of the orient-while-drilling system comprises the arrangement of the tool modules in the bottomhole assembly. The orient-while-drilling system places the steering tool and instrument module, including non-magnetic collars if used, above the power pack and orienting system. The orienting tools are placed proximate to or next to the motor and bit or next to a bent sub followed by a motor and bit. Locating the orienting tool near the motor and bent sub has mechanical advantages in terms of rotating an offset joint, or bent sub, against frictional and drag forces.
In the B J Nowsco system although preferably the steering tool is located uphole from the orienting tool, it is yet connected to a rotating member of the orienting tool such that the steering tool rotates with the rotating member. By such means the steering tool tracks the rotation or orientation of an offset joint or bent sub. A quick release tool is preferably connected between a coiled tubing grapple connect and the steering tool and instrument module assembly. An orienting tool assembly may include the DC motors and hydraulic pumps, a circulating valve if operated off the hydraulic pumps, and the orienting tool or tools. A bent housing or other offset joint may be located immediately below the orienting tool or in or associated with the motor and bent housing. A current belief in the industry is that it is necessary to locate the steering tool as close as possible to the bit. It is the experience of the present inventors that greater advantage is achieved by locating the orienting tool adjacent the motor and bit.
An electric line preferably feeds the DC motors of the power pack. The electric line could also power a release tool. Preferably lines also exist to provide for the real-time communication of data from the steering tool, although other communication means are known and can be used. Real-time surface monitoring of downhole data permits joystick drilling. A feedback control loop can govern the rotating and orienting while drilling.
The orient-while-drilling system is capable of rotating in either direction to any degree, limited only by the piston stroke (in a preferred embodiment up to 400xc2x0) while drilling, at any time. In practice, corrections would probably be made only when the deviation appeared larger than the noise in the steering data. With the orient-while-drilling system the operator is free to manage the weight on bit in order to suit other needs. The weight on bit need not be managed in order to fine tune the orientation of the offset joint or bent sub.
The availability of a downhole electric-over-hydraulic power pack capable of generating high pressure makes available a hydraulic system capable of adjusting the degree of offset of an offset joint, or in terms of a bent sub, the bend angle. The hydraulic system of the power pack could also be utilized to operate a centralizer, including a centralizer with an adjustable diameter which could function as an anchor.
To review uses for the bottomhole assembly incorporating the downhole electric-over-hydraulic power pack, the hydraulic power can be used to set any valve or combination of valves, not just a single function circulation valve. The hydraulic power from the power pack can be used to hydraulically operate an offset centralizer or a hydraulically operated coaxial centralizer. The coaxial centralizer could be of hydraulically variable diameter. A hydraulically operated variable diameter centralizer could be used to anchor the tool through the wellbore in addition to merely centralizing. The downhole electric-over-hydraulic power pack can also be used to set compression tight mechanical packers. The bottomhole assembly, although adapted to be used with coil tubing, is not limited to coil tubing. It could also be advantageously used in many situations with jointed pipe.
An orient-while-drilling system offers a geo-steering method that need not be tied to a predetermined path. The guidance for geo-steering may be result driven, may be real-time data driven, in addition to or in variance from a predetermined path or a predetermined endpoint. With true geo-steering, a predetermined path in a target reservoir may not exist. There may be a general idea as to where to go but the course may be drilled using instruments to follow the reservoir strata, or wheresoever that appears to lead in real-time, based upon real-time data. In the build section of a well a gamma signal can be used to identify rock strata as the build curve develops. The incoming gamma information may dictate adjusting the build design. To the extent a predetermined path exists, it is constantly being changed and modified, optimized and updated.
An alternate embodiment of the bottomhole assembly could include the placement of a check valve or a back pressure valve between the motor and the bit.
It is not necessary for an orienting tool to use rotation to align a bent housing or any other offset joint. Furthermore, rotation need not be imparted through the use of helical gears to translate longitudinal movement into rotation.
In the orient-while-drilling system the axial position of the bent housing is preferably continuously monitored. The spacial position of the bent housing may be periodically calculated. Continually monitoring the axial position of the bent housing allows the operator to correct the position of the bent housing in small increments, as soon as it exceeds an acceptable tolerance span. Such system minimizes large sudden changes of the wellbore which could lead to problems with the well later when it is lined or serviced. The spacial position of the bit is kept thereby more closely on line. Typically, when the spacial position of the bit is calculated, a new intermediate path is determined that merges with some original predetermined path or special target at some point distant from the current location of the bit. The drilling now continues as if the new intermediate path were the original predetermined path.
Although the directional drilling using coil tubing bottomhole assembly is capable of orienting when pulled off bottom, typically it is designed to orient on bottom in conjunction with drilling and preferably continually monitoring the axial position of the bent housing.
Strictly speaking a bent sub is rotated relative to the earth. The instruments in control are set up to measure and control the bent sub""s rotation relative to the earth.
In the orient-while-drilling system the coil is held while drilling at the surface to control the weight on the drill bit, but not the axial rotation of the coil. When there is weight on bit, the coil collapses into a spiral downhole that provides a friction lock, preventing rotating of the upper portion of the coil. Given such friction lock, there is no need to hold the tubing against axial rotation at the surface during orienting-while-drilling maneuvers. If the bit were rotated while pulled off bottom, the tubing might likely have to be held against axial rotation at the surface.
In some circumstances the orienting-while-drilling system will also calculate bit position with respect to the earth while drilling.
What is claimed is the invention substantially as disclosed, including its inventive aspects singley and in combination.
Position of the Orienting Tool
Problem: How much torque is required to orient the toolface of a prior art drilling assembly compared to the instant design? Calculate frictional torque resisting the rotation of a DUCT BHA in open hole. Assume 3 point bending with forces applied at the extreme ends and middle of the BHA. Only the lower portion of the BHA rotates.
Dimensions
BHA:
Length: overall 70 ft
rotating part
(a) 15 ft {NOWSCO}
(b) 35 ft {prior art}
OD: 3.125xe2x80x3
ID: 2.5xe2x80x3
Hole:
ID: 4.75xe2x80x3
Radius of curvature: 80 m
Coefficient of friction between BHA and hole: 0.30
Axial load:
(a)
(b) 3000 lbf
Results
The torques required to overcome frictional drag are as follows:
(a) Instant Design BHA: 2-30 ft lb
(b) Prior Art: 20-300 ft lb
Discussion of Example
The reason for the large spread in the predicted prior art results arises from the much higher probability that their BHA will have to rotate at two contact points instead of one. If the central section of the BHA has to rotate then it encounters a large bearing force against the hole. Since the contact points are highly variable in position the required torque is similarly variable. The location of the orienting tool of the instant design is chosen to avoid the need to rotate the middle section of the BHA.
Orienting While Drilling
The instant orienting tool is designed to provide sufficient torque allow toolface adjustments to be made while the drill bit is working. This requires torques in the range 300-1000 ft lb. The adjustment is infinitely variable in both right and left hand directions. Drilling fluid can be circulated continuously during orienting adjustments so that the drilling process is not interrupted. The prior art tool appears to be unable to produce torques of the magnitude needed for continuously drilling. This is due to its reliance on the working pressure difference between the inside and outside of the tool e.g. typically 1000 psi and the cessation of drilling fluid flow required for resetting the tool. The toolface position is changed in 10 degree increments.
Actuator Design
The instant design is powered by a closed hydraulic system developing typically six times more differential pressure than the prior art tool. Motive power is electric. The prior art design is dependent on the drill motor and bit differential pressure. The instant design makes use of helical teeth or slots in both designs.
Steering Tool
The instant design is operable with a variety of steering tool packages, some of which have been in service for more than 10 years.
Circulating Valve
The instant design contains two methods for bypassing the drill motor assembly.
Bursting Disc: an over pressure rupture disc
A servo controlled 3 way valve which simultaneously opens a bypass port and shuts off drilling fluid from the drill motor assembly.
This feature is essential to the reliability of open hole drilling with low circulation rates. The prior art tool does not have this function.
Safety Release Joint
A surface controlled device for separating the BHA in two parts while also recovering the steering tool assembly. This feature is not included in the prior art design.
Measurement of Downhole Pressures
The instant design includes 2 pressure measuring elements, analogue to digital signal conversion and a multiplexor for transmission of the pressure valves to a surface recording/display package. The prior art tool does not have this function.
Orienting Tool
The rotary actuator used in the Nowsco directional drilling tool still has the highest torque capability of any downhole rotary actuator. This is beneficial as it allows the orienting tool (which includes the rotary actuator) to overcome reactive torques of large downhole motors as well as severe friction drag resulting from the ever tightening build radii requested by our customers.
The use of rotary actuators is not new, indeed our actuator bears several features in common with some surface devices. What makes our tool unique is its very high torque output compared with its diameter. There is one design concept that makes this possible. That is the pressure balancing of the actuator piston. Traditional actuators use large thrust bearings to counteract the large axial forces, developed hydraulically, translated into rotary torque by spiral gears or keys. This axial thrust is so large that it becomes very difficult to fit in bearings capable of handling the load. Various designs have been employed historically to convert axial force into rotary torque. In our case the axial force is developed by hydraulic pressure. It has always been a challenge to generate large torques within a compact diameter, and within a compact length. The two design problems to be overcome are first how to handle the large torque, in our case handled by precision helical gears, and second, how to handle large axial force.
Our invention solves the second problem, to my knowledge uniquely. We construct a pressure balanced actuator shaft. This is achieved by skillfully designing shaft and piston sealing diameters to balance the axial forces on the shaft generated by pressure versus those generated by torque on the helical gears. (A fairly complex equation can be presented showing the relationship employed to determine the diameters required for pressure balance). This reduces the axial load component reacted by a rotary thrust bearing by a factor of about 10:1. This in turn, allows us to build much more compact actuators.
Pressure Balance Definition
Pressure balancing refers to the method of minimizing any axial force imparted on the rotating actuator shaft, relative to the non-rotating housing. In essence, this requires that the pressure cavity used to hold the actuator piston is in the same component as the spiral grove used to induce rotary motion of the shaft. For example, if the piston is housed within a pressure cavity within the shaft, then the spiral groove used to generate torque must also be on the shaft, not in the housing. If the piston is housed in a pressure cavity in the housing, then the spiral groove must be placed in the housing, not on the rotating shaft.
The shown embodiments show the combined use of a straight groove and a spiral groove. It is also possible to achieve pressure balance using two spiral grooves, and a piston housed in a cavity that is intermediate to the shaft and the housing.
Minimizing the axial force on the rotating shaft relative to the fixed housing allows much larger pressures and torques to be derived from the same compact unit, as much smaller rotating thrust bearings are required.
The diagrams show a peg and groove arrangement. The preferred embodiment is to use straight and helical gears, rather than pegs and grooves.
Circulating Valve
This invention is a sub component of the novel directional drilling system for coiled tubing. A circulating valve is a valve that can be opened and closed. When it is closed, all the flow is diverted down the tool string, when it is open, the flow is diverted through a port in the outside of the tool.
Circulating valves were commercially available at the time of this invention. However, there were no circulating valves operated by hydraulic pressure. The Nowsco circulating valve uses a downhole hydraulic pump that can drive traditional hydraulic devices. The use of such a hydraulic drive mechanism has not been previously utilized for the operation of a downhole circulating valve.
The original coil tubing drilling strings all had a weakness in that they did not have circulating valves. The circulating valve is required for drilling operations for one or both of the following reasons:
To permit circulation downhole without operating the downhole drilling motor;
To permit circulating flow rates in excess of what can be safely pumped through the downhole drilling motor to move the drill cuttings up the wellbore.
The instant invention allowed a circulating valve to be incorporated into the drill string in a simple and efficient manner using hydraulic pressure generated by downhole hydraulic pumps. The use of hydraulic pressure allows for reliable operation as simple, proven hydraulic valving can be used to control the device.
The present inventors had the first system incorporating a circulating valve. However, other companies have now also developed circulating valves. These competing valves, to my knowledge, are not operated off hydraulic circuits and will likely prove to be less reliable, or less flexible in operation.
Adjustable Offset Joint
The invention is a new method of achieving a downhole adjustable bent sub for mutli-lateral operations including directional drilling.
The method involves using a downhole pump, used to generate high hydraulic pressures. This hydraulic pressure is then converted to a force used to either straighten, or bend, an adjustable bent housing, or else adjust the offset on an offset centralizer.
The exact mechanism of converting pressure to force, required to achieve movement of the bent sub, can take many forms. It will require either an angled rotary actuator, a rotary swash plate or a linear drive moving a hinged joint, or else an offset centralizer, adjustable by either linear or rotary motion of the centralizer.
The ideal embodiment will provide for a tool with hydraulic feed back, showing whether the tool has changed position or not, and will not permit the possibility of adopting a high side other than that set up on surface, even if the tool malfunctions.
Drilling
Directional drilling has become the most common form of drilling. Further trends have been towards horizontal wells with smaller holes and with tighter build radii. There has also been a trend towards drilling with coiled tubing.
A typical horizontal well consists of two parts, first the build section, which is a curve drilled to take the well trajectory from basically vertical to basically horizontal. The second is the horizontal section itself. These two sections require different tool functions. In the build, the goal is to build angle quickly. The horizontal section requires mostly the maintenance of a straight hole, although some corrections in both azimuth and inclination are invariably required.
Presently, the drilling assembly has to be tripped out of hole so that it can be configured for one of the two drilling sections. This invention would permit both sections to be drilled in a single trip, adjusting the tool configuration downhole, when drilling switches from the build section to the horizontal section. This will save much time in the drilling program. Systems have been developed that attempt to achieve this function, but none so far are commercially and technically viable.
Several other problems associated with directional drilling are solved by this invention. The tool string can be run in and out of the well in the straight position, reducing the risk of the tool hanging up and reducing the size of the surface equipment required. Also more control of the build section can be achieved as the build rate can be adjusted as the build is drilled, for example by drilling a portion of the build with the bent housing straightened.
The novelty with this invention is the use of high pressure hydraulics downhole to achieve the functionality. Using hydraulics allows the generation of large forces, required to operate the tool, and also permits the use of standard hydraulic valving to fulfill feed back and control options.
The instant inventors already have experience in downhole hydraulics, as our orienter and circulating valve are hydraulically driven. Our orienter, unlike all others, is placed directly above the drill motor, meaning that we, unlike others, can easily utilize our orienter hydraulics to operate an adjustable bent sub positioned directly above the motor.
The bottomhole assembly, including the preferred embodiments of the above described tools or subs, was developed initially to operate with a downhole drilling motor. However, in some configurations the BHA is applicable to, and can be advantageously used for, other well operations and applications. The invention, therefore, is not limited to drilling applications.
The BHA was also designed particularly to be connected to and used with coiled tubing. Coiled tubing is particularly favorable for continuous operations, such as orienting while drilling. However, the bottomhole assembly as designed could be used with tubulars, or jointed pipe, at least in some circumstances. Thus, the invention need not be limited to use with coiled tubing.
In operation, a BHA power pack tool of the instant invention would be connected to a source of electricity at the surface. Preferably electric power conveyed by an electric line run through tubing would power a downhole electric motor or motors. Preferably, the electric motors are reversible, DC and structured to comprise a series of motors. For certain operations, such as orienting while drilling, the power pack should generate at least 700 foot pounds of torque in connection with rotating an orienting tool. A hydraulic pump attached both above and below the electric motor(s) makes possible the actuation of double-acting pistons. Clutches can slip the hydraulic pump out of service if riot being used.
When the BHA is used for drilling, the BHA preferably combines its tools such that a steering tool is attached above a power pack which is attached above an orienting tool. The orienting tool is then advantageously located toward the bottom of the BHA, proximate to where attachment is made to a downhole drilling motor and bit and offset joint. Preferably, the orienting tool is located on the bottomhole assembly in proximity to an offset joint. The drilling motor might intervene between the orienting tool and the offset joint, depending upon the motor/offset joint/bit configuration being used. Frequently, the motor/joint/bit unit is leased from third parties. The orienting tool preferably would have two members that in operation rotate with respect to each other. The first member is be adapted to be connected in fixed rotational or axial position to a connecting sub that connects the BHA to the tubing. The second member is adapted to be connected in fixed rotational or axial position to a portion of a steering tool. In operation, thus, this portion of the steering tool and member of the orienting tool is connected in fixed rotational or axial position to a rotating offset joint. Preferably, the BHA includes a release tool attached between a sub connecting the BHA to the tubing and a steering tool. The release tool could be electrically powered. In operation, a release tool so situated can separate the tubing from the bulk of the BHA. Preferably, also the BHA includes a circulating valve. The preferred location for a circulating valve is above the orienting tool for drilling operations. Preferred embodiments of a BHA might also include an adjustable centralizer, and preferred embodiments used for drilling might include an adjustable offset joint. In operation, a downhole adjustable centralizer could be adjusted by using the hydraulics from a power pack. Such an adjustable centralizer might be structured to be adjusted to provide an anchor for the BHA. In operation, an adjustable offset joint could be adjusted downhole to vary the bend angle of the drilling, and could include the option of straight drilling, without tripping out of the hole. An adjustable offset joint could also adopt a straight orientation for running the BHA into and out of the hole. An adjustable offset joint would preferably be located between the orienting tool and the motor.
In operation, an important aspect of the BHA for downhole drilling includes means for communicating wellbore and drilling data to a surface facility. The preferred means of communicating would be by electric line running through tubing. Other reliable means of communicating downhole data, however, exist. The communicating of real time downhole data facilitates orienting while drilling. xe2x80x9cReal timexe2x80x9d data, as that term is used herein, may be communicated essentially continuously and essentially contemporaneously with its collection. Alternately, xe2x80x9creal timexe2x80x9d data might also be packaged and communicated in bursts, lagging a few seconds behind the data""s time of collection. Real time data preferably includes data relating to the axial location of the offset joint, the spacial location of the BHA, and formation and/or reservoir data. Data whose communication lags collection by several minutes would not be regarded as real time.
The invention includes a BHA for use with a downhole drilling motor that includes an orienting tool having a member that defines an end of a piston chamber opposite the piston. This member also has a helical element mating with an element of the piston operable in the chamber to create a balanced pressure orienting tool. The orienting tool has a second member with respect to which the first member notates and preferably the relative rotation is bidirectional and up to at least 360xc2x0 in response to movement of a double-acting piston. Preferably also, the rotation is not limited to fixed steps.
For downhole drilling motor operations, the BHA may include a circulating valve structured to divert a portion of fluid communicated down the drill string, such as the drilling fluid. The fluid is to be diverted around the drilling motor and into the wellbore. An electrically powered hydraulic pump preferably operates such a circulating valve.
A BHA for use with a drill string and downhole drilling motor might include a downhole adjustable offset joint with the offset being adjusted in response to translational movement of a double acting piston. The piston could translate a nonaxially aligned shaft wherein the translation of such shaft creates an offset joint. Adjusting the degree of the offset involves selecting the position of the shaft. The translation of the piston is best activated by an electric-over-hydraulic pump attached to the BHA. Alternately, the degree of offset of an adjustable offset joint could be adjusted by means of two members that are pivotally attached to one another. The degree of offset would be a function of the pivotal relationship between the two elements. This pivotal relationship, in turn, could be governed by the movement of a piston in a chamber.
As mentioned above, the invention may include a bottomhole assembly that has a downhole adjustable centralizer. The centralizer could have a plurality of adjustable arms. Preferably, an electric-over-hydraulic actuator in fluid communication with the piston would connect with the arms and adjust the diameter defined by the arms. Such an adjustable centralizer might provide arms with the capacity to adjust outward such that the centralizer could form a downhole anchor for the BHA. Preferably, the centralizer arms would adjust in response to the movement of a double-acting piston.
The invention is particularly directed to a method of directional drilling that comprises transmitting steering information from a BHA to a surface facility while drilling, determining a steering correction and rotating an offset joint while drilling.
The steering information could include a variety of information. However, some corrections could be based upon minimal information. Preferably, all steering information and downhole data would be processed by a computer facility. The steering information should include information relating to the axial orientation of the BHA. In particular, this information should relate to the axial orientation of an offset joint. The steering information should also include information relating to the spacial location of the BHA. This information may relate to the spacial location of the bit or to any other element along the BHA. Preferably, steering information also includes formation and/or reservoir data. The best steering strategy might be to follow some formation or the reservoir as opposed to any predetermined path, or to aim for a spacial target.
The instant method of directional drilling is particularly applicable to the use of coiled tubing as the drilling string. With coiled tubing as the drilling string, and with practicing orienting while drilling, the drilling need not be stopped to either add a joint to the drilling string or to effect an orientation change.
The steering information should be real time at least at important times, but may be batched and transmitted to the surface periodically, as opposed to substantially continuously, according to the best strategy for data communication with the equipment used.
Given the availability of computer processing of data, especially real time data, as well as reliable communication facilities, the data could be processed and the steering correction determined off-site, as in a central directional drilling facility, remote from the drilling location. In such a manner, one directional driller, and possibly one computer, could manager a plurality of directional drilling operations, even simultaneously.
Preferably, orienting while drilling includes powering a downhole electric-over-hydraulic motor attached to a BHA. The drilling includes operating a downhole drilling motor and drilling element attached to a BHA. Orienting typically includes relatively rotating two elements of an orienting tool. One element remains in fixed axial relationship to the offset joint. The other element remains in fixed axial relationship to the drilling string, or at least to the lower portion of the drilling string attached to the BHA. Drilling strings may well twist or torque between the BHA and the surface during drilling. Preferred orienting tools and methods of the present invention permit rotating an offset joint in varying amounts in two directions and impart temporarily a torque or rotation to at least the lower portion of the drill string while performing the orienting. In preferred embodiments, orienting includes maintaining a portion of the steering module in a fixed axial relationship with the offset joint.
The invention includes a method for orienting an offset joint of a BHA downhole. The orienting includes supplying electricity from the surface to power a downhole electric-over-hydraulic motor associated with a BHA. The method includes hydraulically translating a piston in a chamber in a BHA and converting longitudinal motion of the piston to an adjustment of orientation of an offset joint. The adjustment of orientation of the offset joint might include either adjustment in axial rotation of the offset or adjustment of the degree of offset of the offset joint, or both.
The present invention includes a method of drilling using a downhole motor attached to a BHA that includes the ability to circulate at least a portion of a drilling fluid to the wellbore at the BHA while bypassing the drilling motor. Preferably, the drilling would be performed with coiled tubing and the circulating would use a circulating valve. The invention also includes a method for centralizing a BHA, comprising hydraulically actuating a piston in the BHA and varying a pivot angle in a centralizer link arm in accordance with translational motion of the piston. The invention includes a method of directional drilling comprising hydraulically translating a piston in a chamber in a BHA and varying a degree of offset of an offset joint in accordance with the translation of the piston. The degree of offset might be varied by hydraulically powering a piston in the BHA to achieve a desired pivot angle between two elements in the BHA.